Lobular Carcinoma in Situ (LCIS)

This information explains what lobular carcinoma in situ (LCIS) is, what it means for your risk of developing breast cancer, and what screening and prevention strategies may be right for you.

About LCIS

LCIS is a condition in which there are more cells than usual inside the lobules (small round sacs that produce breastmilk) of your breast. The term “in situ” means “in place,” meaning those cells are only in the lobules.

Although the term LCIS includes the word “carcinoma”, which is another word for cancer, LCIS is not breast cancer. However, it does increase your risk of developing breast cancer. LCIS is diagnosed through a breast biopsy. If your biopsy shows that you have LCIS, your risk of developing breast cancer in either breast is approximately 1% to 2% per year. This risk gradually increases to 10% to 20% in 10 years.

Breast Cancer Screening

Women with LCIS should have regular breast exams and breast imaging tests. You and your doctor will decide what type of breast imaging is best for you, based on your personal history. At Memorial Sloan Kettering (MSK), we recommend a physical exam with a breast specialist every 6 to 12 months, as well as breast imaging every year.

How to Lower Your Risk for Invasive Breast Cancer

Taking medications

Taking certain medications can help lower your risk of getting cancer. For breast cancer, you would take a pill once a day for 5 years. Studies have shown that these medications may lower your risk of breast cancer by more than 50%. Talk with your healthcare provider about the risks and benefits of these options so you can choose the one that is best for you.

Tamoxifen and raloxifene

Tamoxifen (Nolvadex®, Soltamox®) and raloxifene (Evista®) are medications that lower your risk of breast cancer by blocking the effects of estrogen. Estrogen is a hormone that supports the growth of many breast tumors. These medications only reduce your risk of developing estrogen receptor-positive breast cancer, which is the most common type. They will not reduce your risk of estrogen receptor-negative cancers.

You can take raloxifene only if you have already gone through menopause. You can take tamoxifen before or after menopause.

Aromatase inhibitors

Aromatase inhibitors are medications that stop an enzyme called aromatase from changing other hormones into estrogen. These medications are part of the standard treatment for breast cancer in women who have gone through menopause. One of these medications, exemestane (Aromasin®), has also been shown to lower the risk of breast cancer in women with LCIS.

Prophylactic mastectomy

Bilateral prophylactic (PRO-fih-LAK-tik) mastectomy is the surgical removal of both breasts to try to prevent breast cancer. This surgery is rarely used to lower the risk of breast cancer in women with LCIS.

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